Once every four years, the community of scientists engaged in mucosal immunity research convene at the International Congress of Mucosal Immunity (ICMI) to obtain an in-depth overview of their scientific area. The 12th such International Congress will be held in Boston MA on June 25th-30th, 2005 at the Marriott Copley Square Hotel and is being organized under the auspices of the Society for Mucosal Immunity led by Drs. Lloyd Mayer and Richard Blumberg. This meeting will occur over a four day period, each day focused on one of the major scientific areas of interest to mucosal immunologists. This includes days devoted to innate and adaptive immunity, mucosal responses to infections and vaccine development and diseases of mucosal surfaces related to abnormal immune responses. Each day of the meeting will begin with plenary sessions in which both outstanding scientists outside and inside the area of mucosal immunity will speak. These will be followed by Symposia/poster discussion sessions centered on abstracts submitted by meeting participants. Finally, each day will end with addresses from outstanding immunologists who will sum up research in their respective areas of interest with relevance to mucosal immunity. The Congress will focus on basic themes of mucosal immunity including oral tolerance, regulation of mucosal responses, antigen presentation and B cell function in the mucosal immune system. In addition, it will examine diseases due to mucosal immune dysfunction including such major diseases as inflammatory bowel diseases, asthma, and helicobactor infection. Finally, it will devote major attention to mucosal vaccine development, particularly as this elucidates the search for a HIV vaccine. Overall, the Congress is a major and necessary part of the intellectual landscape of mucosal immunity.